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  1. ;functions.asm file
  2. ;------------------------------------------
  3. ; void iprint(Integer number)
  4. ; Integer printing function (itoa)
  5.  
  6.  
  7. iprint:
  8.     push eax             ; preserve ax on the stack to be restored after function runs
  9.     push ecx             ; preserve cx on the stack to be restored after function runs
  10.     push edx             ; preserve dx on the stack to be restored after function runs
  11.     push esi             ; preserve si on the stack to be restored after function runs
  12.     mov  ecx, 0          ; counter of how many bytes we need to print in the end
  13.  
  14.     divideLoop:
  15.         inc     ecx             ; count each byte to print - number of characters
  16.         mov     edx, 0          ; empty dx
  17.         mov     esi, 10         ; mov 10 into si
  18.         idiv    esi             ; divide ax by si
  19.         add     edx, 48         ; convert dx to it's ascii representation - dx holds the remainder after a divide instruction
  20.         push    edx             ; push dx (string representation of an intger) onto the stack
  21.         cmp     eax, 0          ; can the integer be divided anymore?
  22.         jnz     divideLoop      ; jump if not zero to the label divideLoop
  23.  
  24.     printLoop:
  25.         dec     ecx            ; count down each byte that we put on the stack
  26.         mov     eax, esp       ; mov the stack pointer into ax for printing
  27.         call    sprint         ; call our string print function
  28.         pop     eax            ; remove last character from the stack to move spforward
  29.         cmp     ecx, 0         ; have we printed all bytes we pushed onto the stack?
  30.         jnz     printLoop      ; jump is not zero to the label printLoop
  31.  
  32.     pop     esi             ; restore si from the value we pushed onto the stack at the start
  33.     pop     edx             ; restore dx from the value we pushed onto the stack at the start
  34.     pop     ecx             ; restore cx from the value we pushed onto the stack at the start
  35.     pop     eax             ; restore ax from the value we pushed onto the stack at the start
  36. ret
  37.  
  38.  
  39. ;------------------------------------------
  40. ; void iprintLF(Integer number)
  41. ; Integer printing function with linefeed (itoa)
  42.  
  43. iprintLF:
  44.     call    iprint          ; call our integer printing function
  45.     push    eax             ; push ax onto the stack to preserve it while we use the ax register in this function
  46.     mov     eax, 0Ah        ; move 0Ah into ax - 0Ah is the ascii character for a linefeed
  47.     push    eax             ; push the linefeed onto the stack so we can get the address
  48.     mov     eax, esp        ; move the address of the current stack pointer into ax for sprint
  49.     call    sprint          ; call our sprint function
  50.     pop     eax             ; remove our linefeed character from the stack
  51.     pop     eax             ; restore the original value of ax before our function was called
  52.     ret
  53.  
  54.  
  55. ;------------------------------------------
  56. ; int slen(String message)
  57. ; String length calculation function
  58.  
  59. slen:
  60.     push    ebx
  61.     mov     ebx, eax
  62. nextchar:
  63.     ; cmp    ax, 0
  64.     jz      finished
  65.     inc     eax
  66.     jmp     nextchar
  67. finished:
  68.     sub     eax, ebx
  69.     pop     ebx
  70. ret
  71.  
  72.  
  73. ;------------------------------------------
  74. ; void sprint(String message)
  75. ; String printing function  
  76.  
  77. sprint:
  78.     push edx
  79.     push ecx
  80.     push ebx
  81.     push eax ; the number
  82.  
  83.  
  84.     ;call    slen            
  85.     mov edx,1       ; length of string
  86.     mov ecx,esp     ; arg2, pointer to string
  87.     mov ebx,1       ; write to screen
  88.     mov eax,4       ; sysout
  89.     int 0x80        ; call kernel interupt        
  90.  
  91.     pop eax
  92.     pop ebx
  93.     pop ecx
  94.     pop edx
  95. ret
  96.  
  97.  
  98. ;------------------------------------------
  99. ; void sprintLF(String message)
  100. ; String printing with line feed function
  101.  
  102. sprintLF:
  103.     call    sprint
  104.     push    eax
  105.     mov     eax, 0AH
  106.     push    eax
  107.     call    sprint
  108.     pop     eax
  109.     pop     eax
  110. ret
  111.  
  112.  
  113. ;------------------------------------------
  114. ; void exit()
  115. ; Exit program and restore resources
  116.  
  117. quit:
  118.     mov     ebx, 0
  119.     mov     eax, 1
  120.     int     80h
  121. ret
  122. ; %include 'functions.asm'
  123.  
  124. section .bss
  125.  
  126. number: resb 1
  127. 	custom_regs: resd 8  
  128.  
  129. section .text
  130. 	global _start
  131. 	_start:
  132.  
  133.  
  134. ; Init to 0
  135. xor ecx, ecx
  136.  
  137. tenloop:
  138.  
  139. 		inc ecx          ; Incriment    
  140. 		mov eax,ecx      ; Move CX to AX for comparison 
  141. 		test eax, 1
  142. 		jne fail
  143. 		mov eax, ecx
  144. 		add eax,48       ; number + 48 = ascii number+index
  145. 		call sprintLF    ; call your print function 
  146. fail:
  147. 		cmp ecx,8        ; did the counter reach 8? 
  148. jne tenloop
  149.  
  150. end:
  151. call quit
Success #stdin #stdout 0s 148KB
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https://ideone.com/10qsWi
language:
Assembler 32bit (nasm 2.14)
created:
8 years ago
visibility:
public

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